Valve and damper

Abstract

To provide a valve capable of stably generating damping force by omitting a land part or reducing an area of the land part, while improving a degree of freedom in setting damping force characteristics.SOLUTION: A valve V of the present invention includes a piston 2 having a compression side port 2d, and a compression side stacked leaf valve 1 stacked on the piston 2 to open and close a compression side port 2d. The compression side stacked leaf valve 1 includes a first leaf valve 1a stacked on the piston 2 and having a pressure relief hole 1a3 connected to the compression side port 2d, and a second leaf valve 1b stacked on an opposite piston side of the first leaf valve 1a to block a pressure relief hole 1a3. When the compression side stacked leaf valve 1 opens the compression side port 2d, the pressure relief hole 1a3 remains blocked by the second leaf valve 1b.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a valve and a shock absorber. [Background technology]

[0002] A shock absorber is used, for example, by being interposed between the body and axle of a vehicle in order to improve the ride comfort of the vehicle, and suppresses vibration of the body and wheels by the damping force it exerts when expanding and contracting.

[0003] Such a shock absorber includes, for example, a cylinder, a piston rod movably inserted into the cylinder, a piston connected to one end of the piston rod to divide the interior of the cylinder into one chamber and another chamber and having a port connecting the one chamber and the other chamber, and a stacked leaf valve formed by stacking a plurality of annular leaf valves fixed to the piston rod with its inner circumferential side as a fixed end and its outer circumferential side as a free end while being allowed to flex, on the one chamber side of the piston to close the one chamber side opening of the port.The valve is then composed of the piston and the leaf valve.

[0004] The piston also has a boss portion provided on the inner periphery of the opening on one chamber side of the port and against which the inner periphery of the stacked leaf valve is stacked, and an annular valve seat provided on the outer periphery of the opening on one chamber side of the port, surrounding the port and against which the free end side of the stacked leaf valve abuts.

[0005] When the piston moves in a direction that compresses the other chamber, the pressure in the other chamber increases, and the hydraulic oil in the other chamber tries to move through the port to the one chamber where the pressure is lower. The stacked leaf valve then receives the pressure from the other chamber at its front side, which is the side of the piston, and bends the outer periphery, which is its free end, away from the valve seat, opening the port and providing resistance to the flow of hydraulic oil passing through, generating a damping force (see, for example, Patent Document 1).

[0006] On the other hand, when the piston moves in the direction compressing the first chamber, the pressure in the first chamber increases. However, the stacked leaf valve is stacked on the end of the piston on the side of the first chamber, and receives the pressure in the first chamber on its back surface, which is the side opposite the piston, and is pressed against the piston, closing the port and preventing the passage of hydraulic oil. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2021-143696 Summary of the Invention [Problem to be solved by the invention]

[0008] In conventional valves, when the piston moves in the direction that compresses one chamber and the pressure in that chamber increases, hydraulic oil can get in between the first leaf valve, which is positioned closest to the piston and abuts against the piston, and the second leaf valve, which is stacked on the back of the first leaf valve.

[0009] The first leaf valve, whose free end rests on the piston's valve seat, has its inner periphery supported by the piston's boss and its outer periphery supported by the piston's valve seat, but the portion between its fixed end and free end faces the annular recess formed between the piston's boss and the valve seat and is not supported in any way. Therefore, when hydraulic oil enters between the first and second leaf valves, the pressure between the first and second leaf valves increases and the first leaf valve is pressed from its back side, causing the portion of the first leaf valve between its fixed end and free end to bend convexly toward the piston, applying a large amount of stress to the first leaf valve and potentially causing it to fatigue.

[0010] One possible way to reduce fatigue in the first leaf valve is to increase its durability by making it thicker or by increasing its flexural rigidity. However, increasing the durability of the first leaf valve increases the valve opening pressure of the stacked leaf valves, which restricts the degree of freedom in setting the damping force characteristics of the valve.

[0011] Another possible method for reducing fatigue on the first leaf valve is to provide a land portion at the bottom of the annular recess to support the first leaf valve and suppress its deflection. However, providing a land portion on the piston can cause the leaf valve to adhere to the land portion, or contaminants floating in the hydraulic oil can become trapped between the land portion and the leaf valve, making it difficult to generate a stable damping force.

[0012] This problem occurs even when the laminated leaf valve is a floating valve in which the entire leaf valve approaches and closes the valve seat member to open and close the port.

[0013] SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a valve and a shock absorber that can improve the degree of freedom in setting the damping force characteristics and generate a stable damping force. [Means for solving the problem]

[0014] To solve the above problems, the valve of the present invention includes a valve seat member having a port and a laminated leaf valve stacked on the valve seat member to open and close the port, the laminated leaf valve having a first leaf valve stacked on the valve seat member and having a pressure relief hole connected to the port, and a second leaf valve stacked on the opposite side of the valve seat member from the first leaf valve and closing the pressure relief hole, the pressure relief hole remaining closed by the second leaf valve when the laminated leaf valve opens the port. With this configuration, even if liquid gets between the first and second leaf valves when pressure is applied to press the first and second leaf valves toward the valve seat member, the first leaf valve has a pressure relief hole that communicates with the compression-side port, so the liquid that has gotten between the first and second leaf valves is discharged to the compression-side port through the pressure relief hole. Therefore, it is possible to prevent the first leaf valve from being deflected by pressure acting between the first and second leaf valves, and since a large stress that would deflect the first leaf valve toward the valve seat member does not act on the first leaf valve, there is no need to improve the durability of the first leaf valve by increasing its thickness or improving its deflection rigidity, etc. Therefore, it is possible to reduce the thickness of the first leaf valve or reduce its deflection rigidity, so the thickness and deflection rigidity of the first leaf valve can be freely set.

[0015] In the valve of the present invention, the flexural rigidity of the first leaf valve may be equal to or less than the flexural rigidity of the second leaf valve. This configuration prevents the damping force exerted by the valve from becoming excessive, and prevents a deterioration in the ride comfort of a vehicle when a shock absorber equipped with the valve is installed in the vehicle.

[0016] In the valve of the present invention, the thickness of the first leaf valve may be equal to or less than the thickness of the second leaf valve. The first leaf valve is formed by punching a plate-shaped base material with a die, and with this configuration, the first leaf valve has a thin plate thickness, which reduces wear on the die and allows the first leaf valve to be formed with high precision.

[0017] In the valve of the present invention, the first leaf valve may be formed with a plurality of pressure relief holes. With this configuration, liquid that has entered between the first leaf valve and the second leaf valve is quickly discharged to the port from a plurality of locations, preventing part of the first leaf valve from deflecting toward the valve seat member.

[0018] The shock absorber of the present invention includes an outer tube, a shock absorber body having an outer tube, a rod inserted into the outer tube so as to be axially movable, and at least two working chambers through which liquid flows as the rod moves relative to the outer tube, and the valve provided between the working chambers. With this configuration, the shock absorber includes the valve, which improves the design freedom of the damping force characteristics and enables the generation of a stable damping force. [Effects of the Invention]

[0019] According to the valve and shock absorber of the present invention, the degree of freedom in setting the damping force characteristics can be improved, and a stable damping force can be generated by omitting the land portion or by reducing the area of ​​the land portion. [Brief explanation of the drawings]

[0020] [Figure 1] 1 is a vertical cross-sectional view of a shock absorber to which a valve according to an embodiment of the present invention is applied. [Figure 2] FIG. 2 is an enlarged cross-sectional view of the valve of the present embodiment. [Figure 3] FIG. 2 is a plan view of a first leaf valve in the valve of the present embodiment. [Figure 4] FIG. 10 is an enlarged cross-sectional view of the valve during the contraction process. DETAILED DESCRIPTION OF THE INVENTION

[0021] The present invention will be described below based on the embodiments shown in the drawings. As shown in Figure 1, a valve V in one embodiment is applied to the piston portion of a shock absorber D, and includes a piston 2 as a valve seat member having a compression-side port 2d as a port, and a compression-side laminated leaf valve 1 as a laminated leaf valve stacked on the piston 2 to open and close the compression-side port 2d.

[0022] As shown in FIG. 1 , a shock absorber D to which the valve V is applied includes a shock absorber main body A having a cylinder 10 as an outer tube and a rod 11 movably inserted into the cylinder 10, which is extendable and retractable, and a valve V provided between an expansion-side chamber R1 and a compression-side chamber R2 as two working chambers provided in the shock absorber main body A. This shock absorber D is used by being interposed between the body and axle of a vehicle (not shown) to suppress vibrations of the body and wheels. Note that the shock absorber D including the valve V according to the present invention may of course be used for purposes other than vehicles, and may also be used for purposes other than shock absorbers. In this way, the purpose of use of the valve V according to the present invention can be changed as appropriate.

[0023] Below, a detailed description will be given of each part of the valve V and the shock absorber D. First, to explain each part of the shock absorber D, as shown in Fig. 1, the shock absorber main body A includes a cylindrical cylinder 10 with a bottom as an outer tube, a rod 11 movably inserted into the cylinder 10, and a piston 2 as a valve seat member that is connected to the rod 11 and movably inserted into the cylinder 10, and that divides the inside of the cylinder 10 into an extension-side chamber R1 and a compression-side chamber R2 as working chambers.

[0024] A bracket (not shown) is provided at the base end of the rod 11, which is the upper end in Fig. 1, and the rod 11 is connected to one of the vehicle body and the axle via the bracket (not shown). A bracket (not shown) is also provided at the bottom 10a of the cylinder 10, and the cylinder 10 is connected to the other of the vehicle body and the axle via the bracket (not shown).

[0025] In this way, shock absorber D is interposed between the vehicle body and the axle. When the vehicle travels on an uneven road surface and the wheels vibrate up and down relative to the vehicle body, rod 11 moves in and out of cylinder 10, expanding and contracting shock absorber D, and piston 2 moves up and down (axially) within cylinder 10.

[0026] The shock absorber main body A also includes an annular rod guide 13 that closes the upper end of the cylinder 10 and through which the rod 11 is slidably inserted along its inner periphery, forming an enclosed space inside the cylinder 10. A free piston 14 is slidably inserted into the cylinder 10 on the opposite side of the piston 2 from the rod 11.

[0027] A liquid chamber L is formed above the free piston 14 in the cylinder 10, and an air chamber G is formed below it. The liquid chamber L is further divided by the piston 2 into an extension-side chamber R1 on the rod 11 side and a compression-side chamber R2 on the piston 2 side, and the extension-side chamber R1 and the compression-side chamber R2 are each filled with a liquid. The liquid filled in the shock absorber body A may be hydraulic oil, water, an aqueous solution, or other liquid. On the other hand, the air chamber G is filled with compressed air or a gas such as nitrogen gas.

[0028] When the rod 11 retracts from the cylinder 10 during the extension operation of the shock absorber D, the free piston 14 moves upward within the cylinder 10 in accordance with the volume of the retracted rod 11, expanding the air chamber G and compensating for the volume of the rod 11 retracted from the cylinder 10. Conversely, when the shock absorber D retracts, the rod 11 enters the cylinder 10, and the free piston 14 moves downward within the cylinder 10 in accordance with the volume of the entered rod 11, contracting the air chamber G and compensating for the volume of the rod 11 entering the cylinder 10. Note that instead of the free piston 14, a bladder, bellows, or the like may be used to separate the liquid chamber L and the air chamber G, and the configuration of the movable partition that serves as this partition can be changed as appropriate.

[0029] As described above, in this embodiment, the shock absorber D is a single-rod, single-cylinder shock absorber, and when the shock absorber D extends or retracts, the free piston (movable partition) 14 expands or contracts the air chamber G to compensate for the volume of the rod 11 moving in and out of the cylinder 10. However, the configuration for this volume compensation can also be modified as appropriate. For example, if the free piston 14 and the air chamber G are eliminated and an outer tube is provided outside the cylinder 10, and a reservoir for storing liquid and gas is formed between the cylinder 10 and the outer tube to make the shock absorber a twin-cylinder shock absorber, the reservoir may be used to compensate for the volume of the rod 11 moving in and out of the cylinder 10. Note that the reservoir may be formed in a tank separate from the cylinder 10. The shock absorber D may also be configured as a double-rod shock absorber in which the piston 2 is attached to the center of the rod 11 and the ends of the rod 11 protrude from both ends of the cylinder 10.

[0030] The rod 11 has a reduced outer diameter at the tip end, and is equipped with a small diameter portion 11a having a small outer diameter at the tip end, a large diameter portion 11b having an outer diameter larger than that of the small diameter portion 11a and provided above the small diameter portion 11a in FIG. 1, a step portion 11c provided at the boundary between the small diameter portion 11a and the large diameter portion 11b, and a thread portion 11d provided on the outer periphery of the tip end of the small diameter portion 11a.

[0031] The valve V of this embodiment is attached to a rod 11 and applied to a piston portion of a shock absorber D. As shown in Fig. 1, the piston 2 serving as a valve seat member constituting the valve V is annular and fitted onto the outer periphery of the small diameter portion 11a of the rod 11, and is fixed to the rod 11 by a piston nut 15 that is threaded onto a threaded portion 11d of the rod 11. The piston 2 is also attached to the rod 11, and the outer periphery of the piston 2 is in sliding contact with the inner periphery of the cylinder 10, dividing the interior of the cylinder 10 into an expansion-side chamber R1 and a compression-side chamber R2 that serve as working chambers.

[0032] More specifically, the piston 2 includes an annular main body portion 2a, a cylindrical portion 2b provided on the outer periphery of the lower end of the main body portion 2a in FIG. 2, an annular compression side boss portion 2c provided on the inner periphery of the upper end of the main body portion 2a in FIG. 2, compression side ports 2d as a plurality of ports provided at intervals in the circumferential direction on the outer periphery of the compression side boss portion 2c of the main body portion 2a and penetrating the main body portion 2a in the axial direction, and an upper opening of the compression side port 2d together with the compression side boss portion 2c provided on the outer periphery of the compression side port 2d at the upper end of the main body portion 2a in FIG. 2, an annular recess 2f is provided between the compression side valve seat 2e and the compression side boss portion 2c at the upper end of the main body portion 2a in FIG. 2; an expansion side port 2g is provided at the lower end of the main body portion 2a in FIG. 2, opening from the inner peripheral side of the compression side port 2d and opening at the upper end of the main body portion 2a in FIG. 2 toward the outer peripheral side of the compression side valve seat 2e; and an annular expansion side valve seat 2h is provided at the lower end of the main body portion 2a in FIG. 2, between the compression side port 2d and the expansion side port 2g.

[0033] Piston rings 2i are attached to the outer peripheries of the main body 2a and the cylindrical portion 2b, with the outer peripheries thereof in sliding contact with the inner periphery of the cylinder 10. As shown in Fig. 2, the compression-side boss portion 2c is provided on the inner periphery at the upper end of the main body 2a in Fig. 2, is annular, and protrudes upward beyond the annular recess 2f provided on the outer periphery, and has a flat surface at the upper end on which the compression-side laminated leaf valve 1 is laminated.

[0034] The compression side valve seat 2e is annular and is provided on the outer periphery of the upper end of the main body 2a in Figure 2, and functions as a valve seat on which the compression side stacked leaf valve 1 seats and leaves.It protrudes upward beyond the annular recess 2f and the outlet end of the compression side port 2d, and has a flat surface at its upper end on which the compression side stacked leaf valve 1 seats and leaves.

[0035] The compression-side ports 2d are provided at the expansion-side chamber side end of the main body 2a in FIG. 2, which is the upper end of the main body 2a, at equally spaced intervals on the same circumference on the outer periphery of the compression-side boss portion 2c in FIG. 2, and open from the upper end of the main body 2a in FIG. 2, extend along the axial direction, and communicate with the lower end of the main body 2a. The compression-side ports 2d are also located at the upper end of the main body 2a in FIG. 2, and open to the inner periphery of the annular compression-side valve seat 2e. Furthermore, the compression-side ports 2d are located at the lower end of the main body 2a in FIG. 2, and open to the outer periphery of the expansion-side valve seat 2h. In this way, the compression-side ports 2d communicate between the expansion-side chamber R1 and the compression-side chamber R2.

[0036] An expansion-side boss 2j and an expansion-side valve seat 2h arranged on the outer periphery of the expansion-side boss 2j are provided at the lower end of the main body 2a in Fig. 2. The expansion-side boss 2j and the expansion-side valve seat 2h are both annular and protrude in the axial direction from the lower end of the main body 2a, and an annular groove is formed between the expansion-side boss 2j and the expansion-side valve seat 2h.

[0037] The expansion-side port 2g opens from an annular groove between the expansion-side boss portion 2j and the expansion-side valve seat 2h at the compression-side chamber side end, which is the lower end of the main body 2a in Fig. 2, and communicates with the outer periphery of the compression-side valve seat 2e at the upper end of the main body 2a in Fig. 2, thereby connecting the expansion-side chamber R1 and the compression-side chamber R2. In this embodiment, the expansion-side port 2g obliquely penetrates between the compression-side ports 2d, 2d of the main body 2a so as not to interfere with the compression-side port 2d, and opens to the outer periphery of the compression-side valve seat 2e at the upper end of the main body 2a in Fig. 2, and a plurality of expansion-side ports 2g are provided at equal intervals in the circumferential direction of the main body 2a.

[0038] Next, as shown in Figure 2, the compression side laminated leaf valve 1 is formed by stacking multiple leaf valves made of circular annular plates, and is stacked on the upper end of the piston 2 serving as a valve seat member in Figure 2, and is fixed together with the piston 2 to the outer periphery of the small diameter portion 11a of the rod 11.

[0039] The compression side stacked leaf valve 1 has the first leaf valve 1a, which is positioned closest to the piston 2 and abuts against the piston 2, having its inner side abutted against the compression side boss portion 2c as a fixed end 1a1 fixed to the rod 11, and its outer side as a free end 1a2 which is seated and released from the compression side valve seat 2e in a state where it is allowed to bend in the direction away from the piston 2.

[0040] 2 and 3, the first leaf valve 1a has a plurality of pressure relief holes 1a3 provided at equal intervals in the circumferential direction in a portion facing the annular recess 2f and communicating with the compression-side port 2d, and a plurality of notches 1a4 provided at equal intervals in the circumferential direction in the outer periphery. In this embodiment, the pressure relief holes 1a3 and the notches 1a4 are provided independently of each other, but the pressure relief holes 1a3 may also communicate with the notches 1a4.

[0041] The number of pressure relief holes 1a3 is not particularly limited and may be 1. In this embodiment, the pressure relief holes 1a3 are circular holes as shown in Fig. 3, but the shape of the pressure relief holes 1a3 is not particularly limited.

[0042] Furthermore, the second leaf valve 1b stacked on the back side of the first leaf valve 1a is an annular plate with inner and outer diameters equal to those of the first leaf valve 1a, and closes the pressure relief hole 1a3 of the first leaf valve 1a from the back side. Since it is sufficient for the second leaf valve 1b to be able to close the pressure relief hole 1a3 from the back side, the outer diameter of the second leaf valve 1b is not particularly limited as long as the outer peripheral edge of the second leaf valve 1b is positioned more outer than the pressure relief hole 1a3 of the first leaf valve 1a when the second leaf valve 1b is stacked on the back side of the first leaf valve.

[0043] In this embodiment, the thickness of the first leaf valve 1a is equal to or less than the thickness of the second leaf valve 1b, and the flexural rigidity of the first leaf valve 1a is equal to or less than the flexural rigidity of the second leaf valve 1b. However, the thickness of the first leaf valve 1a may be made thicker than that of the second leaf valve 1b, and the flexural rigidity of the first leaf valve 1a may be made higher than that of the second leaf valve 1b.

[0044] 2, a plurality of leaf valves (not shown) and a spacer (not shown) are stacked above the second leaf valve 1b. Furthermore, above the compression side stacked leaf valve 1 in FIG. 2, a circular valve stopper 4 attached to the outer periphery of the small diameter portion 11a of the rod 11 is stacked via a spacer (not shown). When the free end 1a2 of the first leaf valve 1a of the compression side stacked leaf valve 1 bends upward away from the piston 2 in the figure and the upper surface of the outer periphery of the compression side stacked leaf valve 1 abuts against the valve stopper 4, the valve stopper 4 restricts further bending of the compression side stacked leaf valve 1 in the direction away from the piston 2, thereby protecting the compression side stacked leaf valve 1 from excessive stress.

[0045] In the compression-side stacked leaf valve 1, when the free end 1a2 of the first leaf valve 1a is seated on the compression-side valve seat 2e to close the valve, the outlet end of the compression-side port 2d, which is in close contact with the compression-side boss portion 2c and the compression-side valve seat 2e, communicates with the expansion-side chamber R1 only via the notch 1a4. On the other hand, as shown in FIG. 4, when the free end 1a2 is bent by the pressure from the compression-side port 2d side and separated from the compression-side valve seat 2e, the compression-side port 2d is opened and resistance is applied to the flow of liquid passing through the gap generated between the compression-side valve seat 2e and the free end 1a2.

[0046] In this way, when the first leaf valve 1a bends under pressure from the compression side port 2d to open the compression side port 2d, the pressure from the compression side port 2d also acts on the underside of the second leaf valve 1b through the pressure relief holes 1a3 formed in the first leaf valve 1a. However, the total opening area of ​​the pressure relief holes 1a3 is much smaller than the pressure-receiving area of ​​the first leaf valve 1a. In addition, the bending rigidity of the first leaf valve 1a is lower than that of the second leaf valve 1b. Therefore, as shown in FIG. 4, when the first leaf valve 1a bends to open the compression side port 2d, the second leaf valve 1b also bends together with the first leaf valve 1a, and the pressure relief hole 1a3 remains closed by the second leaf valve 1b.

[0047] Furthermore, even if the compression-side stacked leaf valve 1 is pressed toward the piston 2 by the pressure on the expansion-side chamber R1 side and liquid enters between the first leaf valve 1a and the second leaf valve 1b, the first leaf valve 1a is provided with a pressure relief hole 1a3 that faces the annular recess 2f and communicates with the compression-side port 2d, so the liquid that has entered between the first leaf valve 1a and the second leaf valve 1b is discharged to the piston 2 side through the pressure relief hole 1a3 and flows into the compression-side chamber R2 through the compression-side port 2d.

[0048] Furthermore, since a notch 1a4 is formed on the outer periphery of the first leaf valve 1a, even if the compression-side laminated leaf valve 1 closes the outlet end of the compression-side port 2d, the orifice formed by the notch 1a4 allows flow in both directions between the expansion-side chamber R1 and the compression-side chamber R2, and provides resistance to the flow of the passing liquid. Note that the method for forming the orifice can be changed as appropriate. For example, a stamp may be formed on the compression-side valve seat 2e to form the orifice. However, the orifice may be omitted.

[0049] The expansion-side laminated leaf valves 3 are stacked below the piston 2 in FIG. 1. The expansion-side laminated leaf valves 3 are formed by stacking a plurality of leaf valves made of annular plates, and are stacked at the lower end of the piston 2 in FIG. 2 as a valve seat member, and are fixed to the outer periphery of the small diameter portion 11a of the rod 11 together with the piston 2. The inner periphery of the lowermost leaf valve of the expansion-side laminated leaf valves 3 abuts against the expansion-side boss portion 2j, and the inner periphery side fixed to the rod 11 is the fixed end, and the outer periphery side is the free end. Therefore, the expansion-side laminated leaf valves 3 are allowed to bend in the direction away from the piston 2 on the outer periphery side, which is the free end side, and the outer periphery side is seated on and removed from the expansion-side valve seat 2h.

[0050] When the free end of the expansion-side laminated leaf valve 3 is seated on the expansion-side valve seat 2h, it is in close contact with the expansion-side boss portion 2j and the expansion-side valve seat 2h, blocking the outlet end of the expansion-side port 2g that opens between the expansion-side boss portion 2j and the expansion-side valve seat 2h. When the free end is bent by pressure from the expansion-side port 2g side and separated from the expansion-side valve seat 2h, the expansion-side port 2g is opened and resistance is applied to the flow of liquid passing through the gap that is generated between the expansion-side laminated leaf valve 3 and the expansion-side valve seat 2h.

[0051] The valve stopper 4, the compression side laminated leaf valve 1, the piston 2, and the extension side laminated leaf valve 3 configured in this manner are assembled in this order to the outer periphery of the small diameter portion 11a of the rod 11, and then are fixed to the rod 11 by being sandwiched between the piston nut 15, which is screwed to the threaded portion 11d of the small diameter portion 11a, and the step portion 11c of the rod 11.

[0052] The valve V and shock absorber D are configured as described above, and their operation will be described below. First, when the piston speed is in the low-speed range during expansion or contraction of the shock absorber D and the pressure differential between the expansion-side chamber R1 and the compression-side chamber R2 is less than the valve-opening pressure of the expansion-side laminated leaf valve 1 and the expansion-side laminated leaf valve 3, the liquid flows through the orifice formed by the notch 1a4 provided in the compression-side laminated leaf valve 1 from the expansion-side chamber R1 to the compression-side chamber R2 during expansion, and from the compression-side chamber R2 to the expansion-side chamber R1 during contraction. Resistance is then applied to the flow of liquid by the orifice.

[0053] In this embodiment, an orifice is provided only in the compression side laminated leaf valve 1, but an orifice may also be provided in the expansion side laminated leaf valve 3. Alternatively, the orifice in the compression side laminated leaf valve 1 may be omitted, and an orifice may be provided only in the expansion side laminated leaf valve 3.

[0054] Next, a case will be described in which the piston speed during contraction of the shock absorber D is in the medium to high speed range and the differential pressure between the expansion-side chamber R1 and the compression-side chamber R2 exceeds the valve opening pressure of the compression-side laminated leaf valve 1 and the expansion-side laminated leaf valve 3.

[0055] First, when the shock absorber D contracts and the piston 2 moves downward in FIG. 1 at a medium to high speed relative to the cylinder 10, the downward movement of the piston 2 in FIG. 1 causes the liquid in the compression-side chamber R2 to bend the compression-side laminated leaf valve 1 and move to the expansion-side chamber R1 through the compression-side port 2d.

[0056] More specifically, as shown in FIG. 4, when the shock absorber D contracts, the pressure in the compression-side chamber R2 acts on the front surface, which is the underside in the figure, of the compression-side stacked leaf valve 1 through the compression-side port 2d, and the action of this pressure causes the free end 1a2 of the first leaf valve 1a of the compression-side stacked leaf valve 1 to bend and move away from the compression-side valve seat 2e, opening the compression-side port 2d. As a result, the liquid in the compression-side chamber R2 moves to the extension-side chamber R1 through the gap generated between the compression-side stacked leaf valve 1 and the compression-side valve seat 2e.

[0057] Therefore, when the shock absorber D performs a contraction operation, the compression side stacked leaf valve 1 provides resistance to the flow of liquid from the compression side chamber R2 to the extension side chamber R1, increasing the pressure in the compression side chamber R2, and the shock absorber D generates a compression side damping force that hinders the contraction operation.

[0058] Furthermore, when the first leaf valve 1a bends under the pressure in the compression-side chamber R2 and opens the compression-side port 2d, the pressure in the compression-side chamber R2 also acts on the underside of the second leaf valve 1b through the pressure relief holes 1a3 formed in the first leaf valve 1a, but the total opening area of ​​the pressure relief holes 1a3 is much smaller than the pressure-receiving area of ​​the first leaf valve 1a. Therefore, as shown in Figure 4, when the first leaf valve 1a bends and opens the compression-side port 2d, the second leaf valve 1b also bends together with the first leaf valve 1a, and the pressure relief hole 1a3 remains closed by the second leaf valve 1b, so no flow path resistance is generated by the pressure relief hole 1a3.

[0059] As the shock absorber D contracts, the free piston 14 moves downward in FIG. 1 in accordance with the volume of the rod 11 entering the cylinder 10, thereby reducing the air chamber G and compensating for the volume of the rod 11 entering the cylinder 10.

[0060] On the other hand, when the shock absorber D performs an extension operation and the piston 2 moves upward in FIG. 1 relative to the cylinder 10 at a medium to high speed, the upward movement of the piston 2 in FIG. 1 causes the liquid in the expansion-side chamber R1, which is compressed, to bend the expansion-side laminated leaf valve 3 and move to the compression-side chamber R2 through the expansion-side port 2g. Therefore, when the shock absorber D performs an extension operation, the expansion-side laminated leaf valve 3 applies resistance to the flow of liquid from the expansion-side chamber R1 to the compression-side chamber R2, increasing the pressure in the expansion-side chamber R1, and the shock absorber D generates an extension-side damping force that hinders the extension operation. Note that, with the extension operation of the shock absorber D, the free piston 14 rises in FIG. 1 in accordance with the volume of the rod 11 retracted from the cylinder 10, expanding the air chamber G and compensating for the volume of the rod 11 retracted from the cylinder 10.

[0061] Here, when the shock absorber D expands, the pressure in the expansion-side chamber R1 increases, which may cause liquid to enter between the first leaf valve 1a and the second leaf valve 1b, thereby increasing the pressure between the first leaf valve 1a and the second leaf valve 1b. In contrast, in the present embodiment, the first leaf valve 1a of the compression-side stacked leaf valve 1 is formed with the pressure relief hole 1a3 that communicates with the compression-side port 2d. Therefore, even if liquid enters between the first leaf valve 1a and the second leaf valve 1b, the liquid is discharged through the pressure relief hole 1a3 to the piston 2 side and flows through the compression-side port 2d to the compression-side chamber R2.

[0062] Therefore, pressure between the first leaf valve 1a and the second leaf valve 1b does not act to deflect the first leaf valve 1a. Therefore, in this embodiment, the portion of the first leaf valve 1a that faces the annular recess 2f and is not supported by the piston 2 does not deflect in a convex shape toward the piston 2, thereby suppressing fatigue of the first leaf valve 1a.

[0063] Furthermore, since no large stress acts on the first leaf valve 1a from the back side, there is no need to improve the durability of the first leaf valve 1a. Therefore, the thickness of the first leaf valve 1a can be reduced, and the bending rigidity of the first leaf valve 1a can be lowered. In other words, by providing the pressure relief hole 1a3 in the first leaf valve 1a, the thickness and bending rigidity of the first leaf valve 1a can be freely set, thereby improving the degree of freedom in setting the damping force characteristics of the valve V.

[0064] Furthermore, the flow resistance of an orifice varies depending on the size of the flow area of ​​the orifice, but as mentioned above, providing the pressure relief hole 1a3 in the first leaf valve 1a allows the thickness of the first leaf valve 1a to be freely set, thereby improving the degree of freedom in adjusting the flow area of ​​the orifice. Specifically, while it was possible to increase the thickness of the first leaf valve 1a in the past, it was not possible to reduce the thickness of the first leaf valve 1a due to issues with durability against stress acting from the back side. In contrast, in this embodiment, the thickness of the first leaf valve 1a can be made thinner, allowing the flow area of ​​the orifice to be smaller than in the past, improving the degree of freedom in adjusting the flow area of ​​the orifice.

[0065] As described above, the valve V of this embodiment comprises the piston 2 as a valve seat member having the compression side port 2d as a port, and the compression side stacked leaf valve 1 as a stacked leaf valve stacked on the piston 2 to open and close the compression side port 2d, the compression side stacked leaf valve 1 having a first leaf valve 1a stacked on the piston 2 and having a pressure relief hole 1a3 connected to the compression side port 2d, and a second leaf valve 1b stacked on the opposite piston side of the first leaf valve 1a to block the pressure relief hole 1a3, and when the compression side stacked leaf valve 1 opens the compression side port 2d, the pressure relief hole 1a3 remains blocked by the second leaf valve 1b.

[0066] In the valve V configured as described above, even if liquid gets between the first leaf valve 1a and the second leaf valve 1b when pressure acts to press the first leaf valve 1a and the second leaf valve 1b toward the piston 2, the first leaf valve 1a is provided with a pressure relief hole 1a3 communicating with the compression-side port 2d, so that the liquid that has gotten between the first leaf valve 1a and the second leaf valve 1b is discharged to the compression-side port 2d through the pressure relief hole 1a3. This prevents the first leaf valve 1a from being deflected by the pressure between the first leaf valve 1a and the second leaf valve 1b. Therefore, in this embodiment, the portion of the first leaf valve 1a that is not supported by the piston 2 does not bend convexly toward the piston 2, thereby suppressing fatigue of the first leaf valve 1a.

[0067] Furthermore, since no large stress acts on the first leaf valve 1a from the back side, there is no need to improve the durability of the first leaf valve 1a by increasing the thickness of the first leaf valve 1a or improving its flexural rigidity. Therefore, the thickness of the first leaf valve 1a can be reduced or the flexural rigidity of the first leaf valve 1a can be lowered, so the thickness and flexural rigidity of the first leaf valve 1a can be freely set. Therefore, the valve V of this embodiment improves the degree of freedom in setting the damping force characteristics.

[0068] Furthermore, as mentioned above, since no large stress acts on the first leaf valve 1a from the back side, the land portion that supports the first leaf valve 1a at the bottom of the annular recess 2f of the piston 2 can be omitted, or even if a land portion is provided on the piston 2, the area of ​​the land portion can be made smaller than in the past.

[0069] Therefore, in the valve V of this embodiment, problems such as the first leaf valve 1a being stuck to the land portion or contaminants getting caught between the first leaf valve 1a and the land portion, which makes it difficult to generate a stable damping force, do not occur, and therefore it is possible to generate a stable damping force. Furthermore, although the land portion can cause a deterioration in formability when sintering the piston 2, in the valve V of this embodiment, the land portion can be omitted or the area of ​​the land portion can be reduced, so that a deterioration in formability when sintering the piston 2 can be suppressed.

[0070] Furthermore, since the thickness of the first leaf valve 1a can be freely set, when a notch 1a4 is provided on the outer periphery of the first leaf valve 1a to form an orifice, the degree of freedom in adjusting the flow path area of ​​the orifice is improved by changing the thickness of the first leaf valve 1a.

[0071] Furthermore, in valve V of this embodiment, the thickness of first leaf valve 1a is equal to or less than the thickness of second leaf valve 1b. First leaf valve 1a is formed by punching out a plate-shaped base material with a die, but in valve V configured in this manner, the thin plate thickness of first leaf valve 1a reduces wear on the die and allows first leaf valve 1a to be formed with high precision.

[0072] Furthermore, in the valve V of this embodiment, the flexural rigidity of the first leaf valve 1a is equal to or less than the flexural rigidity of the second leaf valve 1b. Conventionally, the flexural rigidity of the first leaf valve 1a had to be increased to improve the durability of the first leaf valve 1a, but in the valve V of this embodiment, the flexural rigidity of the first leaf valve 1a can be reduced by providing the pressure relief hole 1a3 in the first leaf valve 1a. This prevents the damping force exerted by the valve V from becoming excessive, and prevents a deterioration in the ride comfort of the vehicle when a shock absorber D equipped with the valve V is mounted on the vehicle.

[0073] In this embodiment, the thickness of the first leaf valve 1a is made equal to or less than the thickness of the second leaf valve 1b, thereby making the flexural rigidity of the first leaf valve 1a equal to or less than the flexural rigidity of the second leaf valve 1b. However, the material of the first leaf valve 1a may be changed to make the flexural rigidity of the first leaf valve 1a equal to or less than the flexural rigidity of the second leaf valve 1b.

[0074] However, the thickness and flexural rigidity of the first leaf valve 1a can be set arbitrarily, and the thickness of the first leaf valve 1a may be made thicker than that of the second leaf valve 1b, so that the flexural rigidity of the first leaf valve 1a is higher than that of the second leaf valve 1b.

[0075] Furthermore, in the valve V of this embodiment, the first leaf valve 1a is formed with a plurality of pressure relief holes 1a3. In the valve V configured in this manner, liquid that has entered between the first leaf valve 1a and the second leaf valve 1b is quickly discharged from a plurality of locations to the compression-side port 2d, thereby more effectively preventing the first leaf valve 1a from bending toward the piston 2.

[0076] In particular, in this embodiment, the pressure relief holes 1a3 are arranged at equal intervals in the circumferential direction of the first leaf valve 1a, so that liquid that has entered between the first leaf valve 1a and the second leaf valve 1b is discharged uniformly in the circumferential direction of the first leaf valve 1a. This prevents the portion of the first leaf valve 1a far from the pressure relief holes 1a3 from bending toward the piston 2.

[0077] Furthermore, by appropriately changing the number of pressure relief holes 1a3, it is possible to adjust the flexural rigidity of the first leaf valve 1a and thereby adjust the damping force characteristics of the valve V. However, the number of pressure relief holes 1a3 is not particularly limited and may be one.

[0078] The shock absorber D of this embodiment includes a cylinder 10 as an outer tube, a rod 11 inserted into the cylinder 10 so as to be axially movable, a shock absorber main body A having at least an extension-side chamber R1 and a compression-side chamber R2 as working chambers through which liquid flows as the rod 11 moves relative to the cylinder 10, and a valve V provided between the extension-side chamber R1 and the compression-side chamber R2. The shock absorber D configured in this manner includes the valve V, which improves the design freedom of the damping force characteristics and enables the generation of a stable damping force.

[0079] While the two working chambers shown in FIG. 1 are the expansion-side chamber R1 and the compression-side chamber R2, the port may be the expansion-side port 2g, and the valve of the present invention may be applied to a valve that generates an expansion-side damping force. Furthermore, in a case where the shock absorber D is a twin-tube shock absorber that includes an outer shell as an outer tube around the outer periphery of the cylinder and a reservoir between the cylinder and the outer shell, a valve seat member may be provided between the compression-side chamber and the reservoir, and a valve V may be provided between the compression-side chamber and the reservoir. In particular, the first leaf valve 1a and the second leaf valve 1b, which are located on the compression-side chamber side of the valve seat member, are subjected to a large back pressure when the shock absorber D is contracted, and therefore the pressure entering between the first leaf valve 1a and the second leaf valve 1b also increases. Therefore, providing the pressure relief hole 1a3 in the first leaf valve 1a more effectively suppresses fatigue of the first leaf valve 1a.

[0080] Furthermore, in the above description, each leaf valve constituting the compression side laminated leaf valve 1 of the valve V is configured in an annular shape, but the leaf valve may be configured in a shape other than annular.

[0081] In addition, in this embodiment, the compression side stacked leaf valve 1 (stacked leaf valve) opens the compression side port 2d (port) by bending the outer peripheral end of the leaf valve, whose inner peripheral end is fixed to the outer periphery of the rod 11, but the compression side stacked leaf valve 1 (stacked leaf valve) may also be a floating valve in which the entire leaf valve moves toward and away from the piston 2 (valve seat member) to open and close the compression side port 2d (port).

[0082] Although the preferred embodiment of the present invention has been described in detail, modifications, variations and changes can be made thereto without departing from the scope of the appended claims. [Explanation of symbols]

[0083] 1···Compression side stacked leaf valve (stacked leaf valve), 1a···First leaf valve, 1a3···Pressure relief hole, 1b···Second leaf valve, 2···Piston (valve seat member), 2d···Compression side port (port), 10···Cylinder (outer tube), 11···Rod, A···Shock absorber body, R1···Extension side chamber (operating chamber), R2···Compression side chamber (operating chamber), V···Valve

Claims

1. a valve seat member having a port; a laminated leaf valve laminated on the valve seat member to open and close the port, the laminated leaf valve includes a first leaf valve laminated on the valve seat member and having a pressure relief hole communicating with the port, and a second leaf valve laminated on the opposite side of the first leaf valve from the valve seat member and closing the pressure relief hole, When the stacked leaf valve opens the port, the pressure relief hole remains blocked by the second leaf valve. A valve characterized by:

2. The flexural rigidity of the first leaf valve is equal to or less than the flexural rigidity of the second leaf valve.

2. The valve of claim 1.

3. The thickness of the first leaf valve is equal to or less than the thickness of the second leaf valve.

2. The valve of claim 1.

4. The first leaf valve has a plurality of pressure relief holes formed therein.

2. The valve of claim 1.

5. a shock absorber body having an outer tube, a rod inserted into the outer tube so as to be movable in an axial direction, and at least two working chambers through which liquid flows as the rod moves relative to the outer tube; and a valve according to any one of claims 1 to 4, which is provided between the working chambers. A shock absorber characterized by:

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